/*
Follow up for problem "Populating Next Right Pointers in Each Node".

What if the given tree could be any binary tree? Would your previous solution still work?

Note:

You may only use constant extra space.
For example,
Given the following binary tree,
         1
       /  \
      2    3
     / \    \
    4   5    7
After calling your function, the tree should look like:
         1 -> NULL
       /  \
      2 -> 3 -> NULL
     / \    \
    4-> 5 -> 7 -> NULL
*/

/**
 * Definition for binary tree with next pointer.
 * struct TreeLinkNode {
 *  int val;
 *  TreeLinkNode *left, *right, *next;
 *  TreeLinkNode(int x) : val(x), left(NULL), right(NULL), next(NULL) {}
 * };
 */
class Solution {
public:
    void connect(TreeLinkNode *root) {
        TreeLinkNode *cur = root;
        while (cur) {
            TreeLinkNode dummy(-1);
            TreeLinkNode *prev = &dummy, *first = NULL;
            for (; cur; cur=cur->next) {
                if (!first) first = (cur->left)?cur->left:cur->right;
                if (cur->left) {
                    prev->next = cur->left;
                    prev = prev->next;
                }
                if (cur->right) {
                    prev->next = cur->right;
                    prev = prev->next;
                }
            }
            // go to next level
            cur = first;
        }
    }
};

#if 0
class Solution {
public:
    void connect(TreeLinkNode *root) {
        if (root == NULL) return;
        TreeLinkNode dummy(-1);
        for (TreeLinkNode *cur = root, *prev = &dummy; cur; cur=cur->next) {
            if (cur->left) {prev->next = cur->left; prev = prev->next;}
            if (cur->right) {prev->next = cur->right; prev = prev->next;}
        }
        connect(dummy.next);
    }
};

#endif
